Environmental Engineering / Çevre Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4321
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Article Citation - WoS: 40Citation - Scopus: 47Boron in Geothermal Energy: Sources, Environmental Impacts, and Management in Geothermal Fluid(Elsevier, 2022) Mott, A.; Baba, Alper; Hadi Mosleh, Mojgan; Ökten, Hatice Eser; Babaei, Masoud; Gören, Ayşegül Yağmur; Feng, C.; Recepoğlu, Yaşar Kemal; Uzelli, Taygun; Uytun, Hüseyin; Morata, Diego; Yüksel Özşen, AslıThe problem of hazardous chemicals in geothermal fluid is a critical environmental concern in geothermal energy developments. Boron is among the hazardous contaminants reported to be present at high concentrations in geothermal fluids in various countries. Poor management and inadequate treatment of geothermal fluids can release excessive boron to the environment that has toxic effects on plants, humans, and animals. Despite the importance of boron management in geothermal fluid, limited and fragmented resources exist that provide a comprehensive understanding of its sources, transport and fate, and the treatment strategies in geothermal energy context. This paper presents the first critical review from a systematic and comprehensive review on different aspects of boron in geothermal fluid including its generation, sources, toxicity, ranges and the management approaches and treatment technologies. Our research highlights the origin of boron in geothermal water to be mainly from historical water-rock interactions and magmatic intrusion. Excessive concentrations of boron in geothermal fluids have been reported (over 500 mg/L in some case studies). Our review indicated that possible boron contamination in geothermal sites are mostly due to flawed construction of production/re-injection wells and uncontrolled discharge of geothermal water to surface water. The dominancy of non-ionic H3BO3 species makes the selection of the suitable treatment method for geothermal waters limited. Combining boron selective resins and membrane technologies, hybrid systems have provided effluents suitable for irrigation. However, their high energy consumption and course structure of boron selective resins encourage further research to develop cost-effective and environmentally friendly alternatives.Article Citation - WoS: 7Citation - Scopus: 93d Electrode Use in Mdc for Enhanced Removal of Boron From Geothermal Water(Elsevier, 2022) Gören, Ayşegül Yağmur; Ökten, Hatice EserMicrobial desalination cell (MDC) is a significantly promising technology due to its simultaneous features of electricity production, wastewater treatment and desalination. In this paper, the three-dimensional (3D) sponge with activated carbon-chitosan (AC-CS) was synthesized to enhance the efficiency of the MDC system. Effects of operating parameters (boron concentration, electrode surface area, catholyte solution, and activated sludge volume) on MDC performance were also investigated. The MDC with 3D AC-CS anode provided a higher power density of 970 mW/m2, boron removal efficiency of 75.9%, and COD removal efficiency of >90% under optimized conditions. The maximum boron and COD removal efficiencies were 65.6 and 81.4% with the power density of 866.9 mW/m2 for geothermal brine. Moreover, BET analysis showed that the 3D AC-CS anode presented high surface area (230 m2/g) and pore volume (0.202 cm3/g). As an overall result, not only the production of 3D sponge anode electrodes with AC-CS composite was achieved but also desalination and power generation results that were comparable with the literature were presented.Article Citation - WoS: 15Citation - Scopus: 18Simultaneous Energy Production, Boron and Cod Removal Using a Novel Microbial Desalination Cell(Elsevier, 2021) Gören, Ayşegül Yağmur; Ökten, Hatice EserThis paper investigates simultaneous boron removal from aqueous solutions, organic matter removal from industrial wastewater and energy production using a Microbial Desalination Cell (MDC). Anode chamber of the conventional MDC cell was modified to include 3D cubic electrodes as a novel design. Effects of operating parameters, including electrode type (3D-electrode and 2D-electrode), anolyte solution temperature (20 °C, 40 °C, and 60 °C), and activated sludge:wastewater volumetric ratio (S:WW = 1:1, 1:2, and 1:5), on MDC performance were studied. Furthermore, real geothermal water treatment was investigated under optimum operating conditions. Boron and organic matter removal efficiencies and the produced power density results were promising for 3D-electrodes under optimum operating conditions. The maximum boron removal efficiency, COD removal efficiency, and power density were 55.5%, 91.5%, and 9.04 mW/m3 treating real geothermal water at optimum operating conditions. The analyses of Scanning Electron Microscope with Energy Dispersive X-ray spectrometer (SEM-EDX) demonstrated biofilm formation and salt deposition on membrane surfaces, which most probably reduced the performance of MDC. Consequently, our results showed that use of 3D-electrodes was a promising improvement to the conventional configurations with 2-D electrodes since removal efficiencies and energy production were comparable for a more compact electrode structure.